# Error analysis and how values in references are determined

Question 1:Most science textbooks have appendixes that have a value for some physical property of some object. This includes diameter of electrons, viscosity of fluids, boiling points, etc. My question is, are the values presented in such appendixes (or other data bases) averages?

Question 2: Also, suppose I try to calculate the boiling point of water using equations. I then compare my result with data obtained from the CRC Handbook. How would I determine how accurate my result is? Would I use percentages or is there another way to calculate the error? Note: by percentages I mean $$\vert\frac{result-reference\,\,value}{reference\,\,value}\vert\cdot100$$

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